1. Field of the Invention
The present invention relates to a recording method of an optical disc device and a method for determining whether there is an abnormality in the optical disc.
2. Description of the Related Art
An optical disc device generally uses laser power to record data on an optical disc such as a CD (Compact Disc) and a DVD (Digital Versatile Disc). After the laser power is set when the optical disc device is manufactured, the laser power is maintained at an appropriate level by an APC (Automatic Power Control) circuit in an RF (Radio Frequency) IC.
FIG. 1 is a diagram illustrating an optical system-related configuration of an optical disc device according to a related art. As shown in FIG. 1, the optical disc device includes an APC circuit 20 composed of a gain & sample/hold unit 21 and an OP amplifier 22, and an optical pickup 30 composed of a Laser Diode (LD) drive 31 and a Front Photo Detector (FPD) 32. The APC circuit 20 outputs a recording power voltage (VWDC) based both on an FPDO signal received from the front photo detector 32 and a WDAC input voltage applied to the OP amplifier 22. The LD drive 31 drives the Laser Diode (LD) to emit a beam corresponding to the recording power voltage (VWDC) output from the APC circuit 20. The front photo detector 32 detects the beam emitted from the LD, and outputs an FPDO signal corresponding to the detected beam.
The FPDO signal, which has a level corresponding to the beam emitted from the LD, is fed back to the APC circuit 20, and the WDAC input voltage is set to a value corresponding to a desired recording speed or recording power. The WDAC is an input power voltage that is applied to the OP amplifier 22 via an external Digital/Analog Converter (DAC). The APC circuit 20 adjusts the recording power voltage (VWDC) based on the FPDO signal fed back from the front photo detector 32 and the WDAC input voltage. By adjusting the recording power voltage (VWDC) in this manner, the APC circuit 20 allows the recording power to be maintained at an appropriate level set according to the current recording speed.
When a malfunction occurs in the front photo detector 32, light reflected from an optical disc 10 may be incident on the front photo detector 32. When recording is performed at a low recording speed (i.e., with low recording power), the reflection light incident on the front photo detector 32 may cause only a minor problem. However, when recording is performed at a high recording speed (i.e., with high recording power), the intensity of the reflection light incident on the front photo detector 32 increases, thereby having a significant influence on the APC circuit 20. No method has been suggested until now for determining whether or not the disc reflection light is incident on the front photo detector 32 and detecting the intensity of the disc reflection light incident thereon.
According to a related art, if a malfunction occurs in the front photo detector 32, causing the disc reflection light incident on the front photo detector 32 to exceed an allowed range when recording is performed at a high recording speed, then recording is performed with recording power different from the set recording power. This causes abnormal recording sections as shown in FIGS. 2 and 3, thereby lowering the recording quality by the optical disc device.
Furthermore, when the recording quality is lowered due to the malfunction of the front photo detector 32, the user cannot know the lowered recording quality until an after-sale service is received, which makes it difficult to take a quick action against the malfunction of the front photo detector 32.